Conquering Angels
by BlueNeutrino
Summary: When the Doctor runs into the Weeping Angels once again, his less-than-amiable companion thinks she has a way of dealing with them.


_**Conquering Angels**_

**Summary: When the Doctor runs into the Weeping Angels once again, his less-than-amiable companion thinks she has a way of dealing with them.**

**A/N: The character of Dominie Nova in this does feature in a couple of my other stories, so she isn't going to get much background just in this. For the purposes of writing this story I needed a companion who already has some prior knowledge of quantum mechanics, so I wanted to use her. **

**For this story you may need to know about the Schr****ö****dinger's Cat thought experiment, where a cat is locked in a box with a vial of poison that is set to be smashed should a certain unstable atom decay. It's impossible to predict when the atom will decay, but under quantum mechanics it's said to be in both a state of decayed and not decayed until the observation is made, therefore the cat can be seen as being both dead and alive until the box is opened.**

**All of the science included in this is grounded mostly in reality, even if some of the applications of it are exaggerated. I don't want to turn this into a science lesson and get bogged down with explanations, so it will probably leave a lot of readers not fully understanding it, but this is an idea I wanted to play around with. Even though the Weeping Angels made a re-appearance with the Eleventh Doctor, I've written this with the Tenth Doctor because that is how I began to write **_**White Pills **_**and had a very specific reason for it. He may seem a tad OOC, but he does have an annoyed and snappy side that shows through on occasion, and when he's around someone like Dominie I think it's no surprise that this shows through more often.**

**Disclaimer: I own Dominie and that is all. Steven Moffat owns the Angels, as well as being responsible for breaking the exact same laws of quantum mechanics that he used to create them in the first place. Seriously Steven, why did you come up with one of the most creative applications of the Quantum Zeno Effect ever and then ruin it by showing the Angels moving?**

"Don't blink," the Doctor said urgently, staring fixedly straight ahead at the stone figure in front of them.

Confused, Dominie turned to look at him. "What? Why?"

Noticing out of the corner of his eye that she wasn't watching it, he quickly snapped at her to do so. "Keep looking at it. It's quantum locked. As lock as we're watching it it'll stay in its stone form, but if we don't then we're finished."

He didn't exactly see the expression on her face in response to that, but a moment later she'd walked right up to it and reached out a hand to touch one of the stone arms that was brought up in front of its face.

Astounded by the recklessness of that action, he just stared at her. "What are you doing?"

"Well, you've just said it's quantum locked," she replied, turning her gaze away from the angel and giving him a look as if she couldn't understand why he was so shocked. "Under quantum mechanics any kind of interaction counts as observation, so if I'm stood here touching it then it can't exactly turn into whatever other form it has, can it?"

"Also if it touches you then you could end up transported hundreds of years through time and lost forever," he responded, still staring at her and wondering why that hadn't happened yet.

Oddly enough, she didn't seem too bothered by that prospect. "Well, obviously not, since I'm still here."

He still couldn't fathom how she could be so blasé about a situation like this. "You can't know that when you haven't even let go yet. It could be draining your time energy right now and the moment you stop touching it that'll be the trigger to blast you into the Roman era or someplace. Then I'll be the one who ends up coming to get you."

She rolled her eyes. "Make your mind up. You've just said that while it's under observation it's in a fixed quantum state, so if I let go and you're still watching me then nothing will happen."

"While that would be great, Dominie, nobody's ever actually been crazy enough to try touching one in stone form before, so we can't know that for certain."

Again, she just gave him an irritated glare, unable to understand his concern. "Does the term 'Quantum Zeno Effect' mean anything to you? A watched quantum system never changes, no matter how unstable."

Realising she had a point, he relented slightly. "Alright, let's assume you aren't going to get sucked up into the time vortex, but we can't run away from it if you're stood here touching it either. It might be a good idea for us to leave."

She scowled at him. "What's the rush? Go get a hammer and we'll smash it to pieces, then we can run away."

"We can't smash it to pieces. It's practically indestructible. A hammer would barely even scratch it."

She cast a quick glance back over it, looking puzzled. "Why? It's just stone."

"No, it's not," he said with a shake of his head, "It's a single quantum system. Trying to break it would be like trying to split an atom."

"So you're telling me it's like a Bose-Einstein condensate?"

"Yes, if you want to think of it that way."

Again, she glanced over the statue and scowled at it. "What kind of Bose-Einstein condensate is made of rock?"

"Dominie…" He let out a sigh of exasperation that she couldn't grasp just how serious the situation was. "That really isn't the point. We need to get out of here, which we can't do if we let it out of our sight, so just step away from it, slowly, without blinking."

Stubbornly, she didn't move. "Doctor, we can't keep watching it forever. Why don't we do something to stop it coming after us at all? If you go find a mirror and stick it in front of it, then it'll be observing itself and won't ever be able to leave its stone state."

That idea had actually occurred to him before, but he knew that it wasn't really an option. "That wouldn't be a good idea," he explained. "Anything that holds the image of an angel becomes an angel. If you put a reflection in front of it all you'll do is replicate the angel itself."

A look of utter bewilderment crossed her face. "Who came up with that rule?" she said scornfully.

"Nobody came up with it," he answered, growing irritated by how argumentative she was being. "It's just a law of the universe that everything has to obey, like the Pauli Exclusion Principle or Newton's Laws of Motion."

"But it makes no sense. It's like saying if you look at the interference patterns in the double slit experiment you'll turn into an electron."

Emphatically, he shook his head at the flawed analogy. "Think of it as an expansion of the waveform, like if you put the observer of Schrödinger's Cat inside a box."

An expression of concentration crossed her face as she thought that through. "The cat's both dead and alive, but if you put the observer in a box with the original box and they open it, then they observe both states until an outsider comes and asks which one it is. The entire system becomes dependent on the same quantum event, so essentially the observer takes on the role of the cat."

He nodded, relieved that at last they'd found something they seemed to agree on. "Exactly."

"So how do we lock it in its current state without replicating it then?" she said, shattering his illusion that they might actually be thinking along similar lines.

"We can't," he answered, hoping that at last he'd finally be able to get that through to her. "All we can do is run."

Her look of stubborn disagreement didn't abate. "Yes we can. Counterfactual definiteness."

Perplexed, he just stared at her. "What?"

"Observing something without actually observing it. Defusing quantum bombs and that type of thing. You know how that works, right?"

Now it was his turn to scowl. "Yes, of course I do, but how is that going to help us?"

"Set up a dual series of photon splitters and put the angel in one of the paths," she replied, as if that much was obvious. "Then put a screen behind the final photon splitter and point the angel to look at it. If it's standing in the way of one of the paths there won't be an interference pattern on the screen, so the angel will see the single line and end up observing itself. Therefore, it's stuck being stone."

For a couple of moments he just stared at her, astounded by how laterally her thought processes worked and amazed that she seemed to be completely oblivious to the impracticality of that suggestion. "Yes, that's a great idea in theory, but where would we get two giant photon-splitters, a laser beam and a black box big enough to contain it all at such short notice? I don't think doing all that would be any more practical than just running away."

Her triumphant look slowly turned into a glower as the impossibility of that task dawned on her. She was going to have to admit that he was right, and she wasn't going to like it. "Fine," she snapped irritably, "But do I get a point for it being good in theory?"

Wanting to just get out of here, he decided to humour her. "Sure, I'll give you that one," he answered, not wanting to argue any longer, "Now can you just back away from the statue without blinking, and when we're far enough away we'll make a break for it."

Still scowling, she let go of the angel's arm and took several steady steps backwards. "So you wouldn't have thought of it, then?" she challenged petulantly, not wanting to let this drop.

The Doctor clenched his jaw for a moment, wishing that just for once she'd give the stubbornly arrogant argumentativeness a rest. "No I wouldn't," he replied, deciding not to add "_because it has zero chance of actually working" _out loud. If any of his previous companions had made that suggestion to him he would have been amazingly impressed despite its impracticalities, but she was far too smug already for him to want to admit to it.

"Great," she said brightly, apparently satisfied that he'd conceded the argument to her. "I guess I'm still ahead on the good ideas front then."

He resisted the temptation to say, "_It wasn't exactly a good idea," _as she moved out of his line of sight off to his left, but instead just continued to keep his gaze fixed on the angel as they backed away. "Right, Dominie," he said after a few moments, "We're almost at the door to the room. When I say 'now' we'll both just turn and run and try to get back to the TARDIS. I think we're far enough away from the angel to make it." He didn't get a reply to that, but supposed she was probably just sulking that they'd ended up having to go with his idea instead of hers. "Okay…" he said after taking two more steps, "Now run!"

He turned and bolted for the exit, but was surprised to find that he couldn't see Dominie anywhere nearby. It was a mere two seconds before he realised what might have happened, and quickly he stopped running and spun back round again to face the angel. As expected, it had begun chasing him, its form now fixed in stone with its arms reaching eagerly forwards and its lips twisted in a vicious snarl.

But yet Dominie was nowhere in sight.

Letting out a sigh, the Doctor quickly realised that his theory about the delayed energy drain had been right. The angel had been absorbing energy from her all the while she'd been stood touching it, and now that no-one was observing the system anymore it had prompted a quantum jump that sent her who-knows-where in time.

"I told her that would happen," he muttered as he began to back away again, both hoping that the TARDIS would be able to track her mobile phone signal through time without much trouble and wondering if he could get away with leaving her wherever she was for just a little while longer.


End file.
